1. Field of the Invention
The present invention relates to a building influence estimation apparatus and a building influence estimation method for estimating influence of a building on a mobile communication terminal.
2. Related Background Art
Conventionally, estimation of influence of a building on a mobile communication terminal is carried out for purposes such as evaluation of reception intensity of radio waves at the mobile communication terminal. The estimation of the influence of the building on the mobile communication terminal is, for example, determination of a building entry loss (attenuation of a radio wave due to the building) or an indoor/outdoor decision to decide whether the mobile communication terminal is located inside the building.
One of such technologies is a method of transmitting radio waves from a communication device into respective directions and detecting reflected waves from an obstacle. In this method, the reflected waves from four directions are detected and if an obstacle is detected from the four directions, it is determined that the device is located indoors (e.g., cf. Japanese Patent Application Laid-open No. 2003-283509 (Patent Document 1)). There is another method of detecting NLOS (Non-Line-Of-Sight) from delay profiles of received waves, at the mobile communication terminal (e.g., cf. H. Shimizu, H. Masui, M. Ishii, and K. Sakawa, “LOS and NLOS path-loss and delay characteristics at 3.35 GHz in a residential environment,” IEEE Antennas and Propagation Society International Symposium, 2000, pp. 1142-1145 vol. 2 (Non-patent Document 1)). There is a further proposal of a method of obtaining the electric field intensity in a building by calculation (e.g., cf. Japanese Patent Application Laid-open No. 2005-318308 (Patent Document 2)).